The present invention relates generally to electrical switches, and more particularly, to a remote switching system that permits remote turn-on and turn-off of an electrical outlet using existing conventional wall switches.
This invention is intended to be used with the electrical wiring system of a residence or other building. In particular, it is the purpose of this invention to provide a means, without any wiring change, for extending the function of an already existing switch, such as a wall switch, to the new function of switching the electrical power available at one or more additional already existing electrical outlets.
In the electrical system of a residence or other building, (e.g., 120 or 220 volt AC), the electrical wiring of that system is relatively permanent in that any significant functional change to that wiring system typically entails access through wall surfaces to the wiring and oftentimes access above the ceiling or below the floor in order to perform rerouting of the wiring. A frequent need for such a wiring change is to extend the function of an existing wall switch (or equivalent switching device) so that, in its new function, it switches electrical power at one or more additional existing electrical outlets. The wiring rerouting entailed in such a change is a significant undertaking.
U.S. Pat. No. 4,200,862 discloses a remote AC power control system. Its basic system configuration includes a control unit, and a companion plug-in remote receiving unit. That system is not intended to extend the function of an existing AC switch. Instead, its purpose is to provide a separate control unit having one or more integral push buttons to control the AC power available from a switched AC outlet integral to the companion plug-in remote receiving unit.
The control unit of this system incorporates one or more user-selectable push (selector) buttons, and, in one embodiment, the control unit incorporates an AC power cord that is plugged into a convenient AC outlet. The remote receiving unit is plugged into an AC outlet where remotely controlled switched AC power is desired. Incorporated into that remote receiving unit is an integral switched AC outlet receptacle into which a lamp or other device can be plugged. In this control unit, encoded switching control signals generated therein are relayed as a modulated carrier frequency via the AC power line to the companion remote receiving unit for control of AC power available from that remote receiving unit's integral AC outlet receptacle.
This system also includes a variant wherein the control unit is battery-powered from an internal battery, and therefore is highly portable. That version of the control unit utilizes a low power transmitter to relay encoded switching control signals to an auxiliary relay unit. The auxiliary relay unit serves an intermediate function, as will be described below.
When one of the buttons on the battery-powered control unit is user-actuated, a corresponding encoded switching control signal is generated and transmitted by its internal low power RF transmitter to the auxiliary relay unit. That auxiliary unit is also plugged into another AC outlet and receives and demodulates the encoded switching control signals. These demodulated signals are then remodulated onto a lower frequency carrier and relayed over the AC power line on to a remote receiving unit. That auxiliary relay unit also incorporates an integral switched AC outlet receptacle responsive to the switching control signals received from the control unit.
All of these units provide user-selection (unit code selection) of the detail of the encoding of the switching control signals thereby circumventing interference with other nearby units. Encoding detail is also changed to prevent ambiguity in the switch-on and switch-off control signals sent to the remote switching unit. In some versions of this system, means are also included for dimming (as well as switching) a lamp plugged into the integral switched AC outlet of the remote receiving unit.
Another variant of the above-described AC power control system uses a control unit of the type described above to remotely switch the AC power at an existing already switched AC outlet. This variant circumvents the need for a plug-in remote receiving unit at that AC outlet. Instead, in this system variant, the wall switch of an existing AC outlet is removed and replaced by a new switching device that incorporates its own switch to replace the one that is removed. The new switching device responds to switching control signals relayed over the AC line from the control unit and switches power to the wired switched AC outlet. The switch built into the new switching device can also be used to turn on or off the AC outlet the same as before the change.
Although the latter system variant provides an additional means for controlling the AC power to an existing already wired AC outlet, it requires removal and disconnection of the AC wiring to the existing switch, replacing that switch with the new switch-mounted switching device having its own switch, and reconnecting the AC wiring thereto.
U.S. Pat. Nos. 5,239,205 and 5,340,954 also disclose a system for providing a remote AC power switching function. It is a two-unit system in which one unit includes a separate switch control unit incorporating its own toggle switch. Its companion remote switching unit is plugged into a remote AC outlet, and incorporates an integral switched AC outlet receptacle into which a lamp or other device to be switched is plugged. Switching control signals in the form of a short-duration modulated RF carrier are transmitted from the switch control unit via a low power wireless RF link to the remote switching unit. Internal battery power is utilized to supply the circuits in the switch control unit.
The toggle switch on the switch control unit has a single set of momentary contacts that close only at the center of each switch transition from one end position to the other. Closure of the momentary contacts initiates the transmission of a switching control signal in the form of a short-duration modulated RF carrier over the RF link.
In one embodiment, the companion remote switching unit is plugged into an existing AC outlet and has incorporated therein an integral switched AC outlet receptacle into which can be plugged a lamp to be switch controlled. In that remote switching unit, an RF receiver is utilized to detect and demodulate the RF burst comprising the switching control signals. Each receipt of that switching control signal toggles between an "on" and "off" state the AC power to its integral switched AC outlet receptacle. In another embodiment of that system, the remote switching unit is configured to screw into a lamp socket and incorporates an integral socket to accommodate the lamp bulb.
As disclosed in U.S. Pat. Nos. 5,239,205 and 5,340,954, modulation frequencies and carrier frequencies utilized for relaying the switching control signals between the switch control unit and the remote switching unit are set at manufacture. Therefore, if more than one switch control unit and remote switching unit pair is to be operated nearby to another pair, it is necessary to select each pair so that their modulation and/or carrier frequencies do not duplicate and thereby interfere with those of another pair.
Also, as disclosed in U.S. Pat. Nos. 5,239,205 and 5,340,954, an identical switching control signal is transmitted to the companion remote switching unit for the "switch on" and "switch off" commands, and a delay of a minimum of 1 second must lapse after the switch is toggled before the switch is toggled again, otherwise the system will not operate properly, i.e., the system can become "out of synch" so that the end positions of the switch toggle may become reversed in function. Because of this limitation, the switch toggle position does not provide a sure indication of whether AC power is on or off at the outlet receptacle of the remote switching unit.
Accordingly, it is an objective of the present invention to provide for a remote switching system that permits remote turn-on and turn-off of an electrical outlet using existing conventional wall switches, and that overcome the limitations of the above-described conventional systems.